I used to do it like this:

Lightly sand all of the area you want resurfaced
Use masking tape to keep nice clean edges - either ducktape or another textile-based tape works the best. Remember: you don't have to stick to the original area - extend it forward if you want to
Apply paint or varnish - epoxy or polyester based are the best. Do it quickly in a (hopefully) even layer all over the whole area.
As soon as the whole area is covered, cover with sugar. About 1/2 kg is enough for the job. Take care it gets to the edges.
Leave to dry - 24-48 hours to be safe
Wash the sugar off with water. Check how sharp the surface is - you may have to gently sand it down to avoid getting bruised badly.

A few tips: you want thick paint or varnish, something that will make a nice layer
Sugar - the coarser the better, but not that unrefined sugar that sticks together. It must be loose like dry sand.
After you've put the sugar on the paint, do not touch. You want the sugar on the surface, not underneath the paint.


It's pretty straightforward. Good luck mate
Honza

Paint or varnish can discolour after time and sugar tends to not last all that long. You can buy non slip in a tin but it never worked that well for me and discoloured again and you will only get 2 boards done out of it. My way is...

Go get some UV stabilised epoxy and some non skid agregate from a marine shop (get the fine stuff like fine white sand not glass beads as they expand when put on the epoxy). After the prep previously mentioned put a light coat of epoxy on and then sprinkle the agregate over the top, do this with a pepper shaker or similar. I put a fair bit of agregate on as you dont want any uncovered areas of epoxy or it will be slippery.

I've done a few boards now and the grip lasts. Where abouts are you btw?

That is used for poly resin boards, it is probably the mildest form of non skid and is good on mast sleeves etc, it can still get a little slippery. If you do this go to surfboard shaper and ask for the resin they use to make their boards, it is ultra clear (I pay about $10 per litre of resin with catalyst and wax for this stuff from shaper). Fish's are epoxy boards plus you might want a bit more grip if doing freestyle.

the redeck mix was what i was talking about, i dont like it. The agregate i like is International - intergrip. The container i have is 450 grams which is probably enough to redeck every board on the east coast or alternatively a small cruise ship .